1. Field of the Invention
The present invention relates to a shed-forming device for a weaving loom incorporating at least one electrical actuator. The invention also relates to a weaving loom comprising such a device.
2. Brief Description of the Related Art
On a loom, it is known to use a set of heddle frames to form the shed. These heddle frames are driven by a pulling system which may itself be operated by a dobby or, alternatively, by means of electrical actuators. FR-A-2 856 412 thus describes a shed-forming device, the pulling system of which is connected, for each heddle frame, to an electrical actuator undergoing a rotary oscillating movement.
The electrical actuator includes in this case a self-contained assembly incorporating an electric motor surrounded by its casing. To receive the electric power on the one hand and to exchange electrical signals with control/drive means on the other, the electrical actuator is provided with two connectors intended to be respectively connected to a line for supplying electric current and to a line for transmitting signals to control/drive means via a panel. Thus, the control/drive means that transmit the electric power to the motor and exchange signals are located at some distance from the motor, for example within a control cabinet common to several actuators.
A shed-forming device comprises several heddle shafts or heddle frames, generally around twenty, which have to be operated individually. To do this, the drawing system of the device must be connected, for each heald shaft or heddle frame, to an actuator associated with remote control/drive means transmitting the power and controlling the control/drive signals by electrical circuits that must be independent of one another. This means installing, between the control cabinet and the actuators, as many electrical power and signal lines for the control/drive as there are actuators. This makes the connection operations lengthy, and therefore expensive. In addition, this requires particular measures to be taken to avoid electromagnetic interference on the control/drive signals by the currents flowing in the many neighbouring electrical lines.
Furthermore, the distance separating an actuator from its control/drive means involves the use of two cooling systems for protecting, on the one hand, the control/drive means and, on the other hand, the motor from the effects of excessive heating. Now, having to fit two cooling circuits for the flow of heat-transfer fluids also increases the manufacturing cost of the installation.
U.S. Pat. No. 6,909,210 describes an electrical actuator which is dedicated to a motor vehicle and comprises an electric motor unit housed in a casing between two flanges. The rear flange furthermore includes an electrical circuit and has a cooling circuit. Each of the flanges houses a rolling bearing, for forming a bearing for the drive shaft. The rear flange is therefore linked closely and directly to the motor unit via a rolling bearing. This rear flange therefore undergoes vibrations and heating generated or transmitted by the rolling bearing in service. This may eventually risk degrading the integrity of the flange on the motor unit and therefore the sealing of the cooling circuit. Such an actuator cannot therefore be included in a shed-forming device since the vibrations therefrom are of particularly high frequency and intensity. Furthermore, since the flanges are closely linked to the motor unit, assembly and disassembly of the actuator, for fitting it or maintaining it, are relatively expensive.